Plastic pollution in freshwater ecosystems: macro-, meso-, and ... Monit Assess (2017) 189.581.pdf · of macro-, meso-, and microplastic fragments in shore-line sediments of a freshwater

Plastic pollution in freshwater ecosystems: macro-, meso-,and microplastic debris in a floodplain lake

Martin C. M. Blettler & Maria Alicia Ulla &

Ana Pia Rabuffetti & Nicolás Garello

Received: 16 June 2017 /Accepted: 12 October 2017# Springer International Publishing AG 2017

Abstract Plastic pollution is considered an importantenvironmental problem by the United Nations Environ-ment Programme, and it is identified, alongside climatechange, as an emerging issue that might affect biologicaldiversity and human health. However, despite researchefforts investigating plastics in oceans, relatively littlestudies have focused on freshwater systems. The aim ofthis study was to estimate the spatial distribution, types,and characteristics of macro-, meso-, and microplasticfragments in shoreline sediments of a freshwater lake.Food wrappers (mainly polypropylene and polysty-rene), bags (high- and low-density polyethylene), bot-tles (polyethylene terephthalate), and disposable Styro-foam food containers (expanded polystyrene) were thedominant macroplastics recorded in this study. Contraryto other studies, herein macroplastic item surveys wouldnot serve as surrogates for microplastic items. This isdisadvantageous since macroplastic surveys are relative-ly easier to conduct. Otherwise, an average of 25mesoplastics (mainly expanded polystyrene) and 704microplastic particles (diverse resins) were recordedper square meter in sandy sediments. Comparisons withother studies from freshwater and marine beaches

indicated similar relevance of plastic contamination,demonstrating for the first time that plastic pollution isa serious problem in the Paraná floodplain lakes. Thisstudy is also valuable from a social/educational point ofview, since plastic waste has been ignored in the Paranácatchment as a pollutant problem, and therefore, theoutcome of the current study is a relevant contributionfor decision makers.

Keywords Plastic pollution .Macro-, meso-, andmicroplastic . Floodplain lake . Endanger environment .

FT-IR spectrophotometer

Introduction

Plastics are already present in sufficient numbers to beconsidered as one of the most important types ofBtechnofossil^ that will form a permanent record ofhuman presence on Earth (Zalasiewicz et al. 2016).For decades, humans have been disposing plastic wastein the sea and rivers, causing beach and water pollution(Faure et al. 2015a, b). At present, plastic pollution isconsidered a crucial environmental problem (UNEP2014), and it is identified alongside climate change asan emerging issue that might affect human health andbiological diversity in the near- to medium-term future(Sutherland et al. 2010).

Despite wide research efforts investigating plastics inoceans, little studies have focused on freshwater systems(Wagner et al. 2014). Thus, there is a relatively lack ofknowledge on plastic waste occurrence in river water

Environ Monit Assess (2017) 189:581 https://doi.org/10.1007/s10661-017-6305-8

M. C. M. Blettler (*) :A. P. Rabuffetti :N. GarelloInstituto Nacional de Limnología (INALI; CONICET-UNL),Ciudad Universitaria, 3000 Santa Fe, Argentinae-mail: [email protected]

M. A. UllaInstitute of Research on Catalysis and Petrochemistry, INCAPE(FIQ, UNL-CONICET), Santiago del Estero 2829, 3000 Santa Fe,Argentina

and sediment worldwide. Data on their presence,sources, and fate is still scarce (Thompson et al. 2009;Eerkes-Medrano et al. 2015). The same is true for theirchemical burden and ecological/physiological effects.

However, in raising questions about the origin andrisk posed by plastic litter in freshwater environments,some studies should be emphasized. Most of these re-searches have focused on lakes, for instance the GreatLakes (Eriksen et al. 2013), Victoria Lake (Biginagwaet al. 2016), and alpine lakes (Imhof et al. 2013). Otherstudies concentrated on river systems, e.g., the Danube(Lechner et al. 2014), Thames (Morritt et al. 2014),Tamar (Sadri and Thompson 2014), Los Angeles(Moore et al. 2011), Rhine and Main rivers (Kleinet al. 2015).

As plastic breaks into smaller pieces (microplastics),it is more likely to infiltrate food webs (Browne et al.2008). Studies have proved that freshwater invertebratesand fish can ingest plastic particles, causing injuries,stress, contaminant bioaccumulation, and tumor forma-tion; immune response disrupting feeding; and alteringmetabolic function (e.g., Rosenkranz et al. 2009; Imhofet al. 2013; Sanchez et al. 2014; Biginagwa et al. 2016).As a result, estimations of particle composition (type ofplastic conforming it) are a key point to determinepotential risks to the environment since many plasticsare chemically harmful, either because they are toxic orbecause they absorb other pollutants (Teuten et al. 2009;Rochman et al. 2013).

Most plastic pollution studies focused on micro-,meso-, or macroplastics. Very few of them reported allsize ranges (e.g., Noik and Tuah 2015). Because thereare no antecedents of plastic contamination in shoresediments of the Paraná River system, we included inthis study the three size ranges.

Considering the above, the aim of this study was toestimate the spatial distribution, types (resin composi-tion and origin), and characteristics (color, shape, size)of macro-, meso-, and microplastic fragments in shore-line sediments of a freshwater lake.

Methodology

Study area

The Paraná is ranked ninth among the largest rivers ofthe world according to its mean annual discharge to theocean (18,000 m3 s−1; Latrubesse 2008), supporting 19

large cities (with a population greater than 100,000inhabitants) and having a great ecological, cultural,and economic importance. This river has a large flood-plain area with thousands of permanent and semiperma-nent lakes and ponds, which support one of the mostdiverse biotic community in the world (Wong et al.2007). The current study was performed in the SetúbalLake, one of the larger floodplain lakes of the ParanáRiver (Fig. 1). This shallow lake has a surface area of32 km2, an average depth about 2 m, and a waterresidence time of 0.002 year (Pecorari et al. 2006). SantaFe City (653,000 inhabitants) extends along the westernshore of the Setúbal Lake, with rubbish dumps andstorm sewers directly discharging into the lake.

Sampling trip

Prior to conducting the sampling, some backgroundinformation on the lake shores was documented suchas morphological features and human interventions (i.e.,concrete groynes), based on the NOAATechnical Mem-orandum (Lippiatt et al. 2013). Since the lake shores areused for recreational purposes during the summer sea-son, the sampling was performed before starting it (De-cember 2016). This was to avoid the sporadic andtemporal influence of beachgoers during the summerseason.

Macroplastic sampling

Many authors noted the difficulty in comparing dataamong plastic pollution studies (Ryan et al. 2009). Thisdifficulty is largely owing to differences in samplingprotocols. In order to make direct comparisons withother studies, we adopted the most widely usedmethods. Referring to the size ranges, the plastic debriswas termedmicro- (≤5mm), meso- (5mm to 2.5 cm), ormacroplastic (> 2.5 cm), since they have been adoptedby UNEP (Cheshire et al. 2009), MSFD Technical Sub-group on Marine Litter (2013), and NOAA (Lippiattet al. 2013).

With the aim to obtain a reliable estimation of plasticlitter, two transects of 50 m in length and 5 m wide wereselected for the macroplastic survey (Noik and Tuah2015). Transects were chosen on higher and lower pol-luted areas of the beach, based on a previous visualinspection (transects 1 and 2, respectively; Fig. 1), in-volving the most recent flotsam line and covering morethan a 20% of the shoreline section, as recommended by

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Lippiatt et al. (2013). Macroplastic items were visuallycollected by hand and transferred to the laboratory forfurther analyses. The macrodebris item concentration(number of debris items m−2) per transect was calculatedas follows (Lippiatt et al. 2013):

c ¼ nw lð Þ

c concentration of debris items (no. of debris itemsm−2).

n no. of macrodebris items observed.w transect width (m).l transect length (m).

The same equation was also used to estimate theweight, area, volume, and length of macroparticles(macroplastics were also referred to the no. of itemsper 250 m2—50 × 5 m—and even per 100 m2).

Mesoplastic sampling

Mesoplastics were collected from triplicate samples(1 m2 quadrats) located in the line of the macroplastictransects (Lippiatt et al. 2013). Once the quadrat place-ment was selected, we collect the top 3 cm of sandsediments. Each sample was sieved in the field using a

stainless steel 5 mm mesh size, removing any pieces ofmesoplastics. Mesodebris particles were transferred tothe laboratory for further analyses.

The mesodebris item concentration (number of de-bris items m−2) was calculated as follows (modifiedfrom Lippiatt et al. 2013):

c ¼ na

c concentration of debris items (no. of debris itemsm−2)

n no. of debris items observed.a area sampled.

The same equation was also used to estimate weight,area, volume, and length of mesoparticles.

Microplastic sampling

As in the case of mesoplastics, samples for microplasticswere collected per triplicate from macroplastic transectsemploying the quadrat method (25 × 25 × 3 cm; Kleinet al. 2015).

Once the Bmicroquadrat^ placement was selected, weremoved the top 3 cm of sand sediments using a smallstainless steel shovel. Sediment samples were

Fig. 1 Study area in the Paraná River floodplain and the specific sampling location on the shoreline of Setúbal Lake

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transferred to the laboratory for further analyses. Eachsample was equivalent to 1.8 kg of dry sand,approximately.

The same equation as in the case of mesoplastics wasalso used to estimate the number of items, weight, area,volume, and length of microplastics.

Processing samples

Macroplastic identification

Collected macroplastic debris were washed, counted,measured, weighed, and classified in the laboratory(item by item). Macroitems were classified taking ac-count their functional origin (e.g., food wrappers, bev-erage bottles, cups, shopping bags, etc.) according to theNOAA Technical Memorandum (Lippiatt et al. 2013)and type (hard plastic, foam, film, etc). Additionally, theASTM (American Society for Testing and MaterialsInternational) International Resin Identification CodingSystem (RIC, Standard Practice for Coding PlasticManufactured Articles for Resin Identification 2016)was used to identify the plastic resin used inmanufactured macroarticles (Gasperi et al. 2014). Thelater procedure was not always possible since the ASTMcode was not always visible. In these cases, we com-piled information based on the product functionality andmost commonly used resin (e.g., Driedger et al. 2015).

Mesoplastic identification

Mesoplastics were classified into hard plastic fragments,foam, films, and others (Gündoğdu and Çevik 2017).Furthermore, number of items, weight, area, volume,length, and color were recorded. Mesoplastic volumewas estimated through the water displacement method(Archimedes’ principle), using graduated cylinders andpipettes. As many plastics float, they were individuallypricked and forced to sink using very thin needles ofnegligible volume.

Microplastic separation and identification

Drying, sieving, and density separation

Microplastic separation was performed according toMasura et al. (2015). In this regard, full samples weredried 60 °C per 24 h, weighed, and sieved through astainless steel sieve with 350 μmmesh size (45) using a

Retsch™ sieve shaker. All material left above the sievewas transferred to a 1-L beaker for wet peroxide oxida-tion, and 30% hydrogen peroxide at 4:1 proportion wasadded to the sample. The mixture was placed on a hotplate set to 60 °C, and the reaction was allowed tocontinue until all organic material disappeared(Yonkos et al. 2014). Hydrogen peroxide was complete-ly washed from the sampling through a 350-μm meshsize, using distilled water.

After the full dissolution of the organic matter, aconcentrated saline NaCl solution (1.2 g cm−3) wasadded and strongly stirred for about 1 min (Hidalgo-Ruz et al. 2012; Yonkos et al. 2014). Subsequently, thesupernatant with the plastic particles was extracted andwashed with distilled water for further processing. Thisstep was repeated as many times as it was needed inorder to ensure the absence of plastic particles betweensand sediments.

Microscope examination

Careful visual sorting of residues was necessary to sep-arate the plastics from other materials, such as shell, fishbones, and scale fragments, as well as other no naturalparticles (metal paint coatings, glass, aluminum foil,etc.). This procedure was performed under a Boeco™zoom stereo microscope and a Nikon™ binocular mi-croscope with a magnification range of ×10–40. Micro-scopic examinations were repeated three times, to besure all plastic particles were properly identified. Thecriteria advanced by Norén (2007) were used to define aplastic particle: (i) no cellular or organic structures werevisible in the plastic particle/fiber; (ii) if the particle wasa fiber, it should be equally thick, not taper toward theends, and have a three-dimensional bending (not entire-ly straight fibers which indicates a biological origin);and (iii) clear and homogeneously colored particles.

Microplastics were classified into hard plastic frag-ments, fibers, foams, and films (Gündoğdu and Çevik2017). Subsequently, number of items, weight, area,volume, length, and color were recorded for each itemcategory (Castañeda et al. 2014). Microparticles wereweighed using a Mettler Toledo™ analytical balance(readability of 0.1 mg).

Fourier transform infrared (FT-IR) spectrophotometer

FT-IR Spectrophotometer Shimadzu IR Prestige 21™was used to analyze the particles of doubtful origin in

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order to confirm (or reject) their plastic composition.This is an optimal means of polymer identification(Song et al. 2015) and is widely used in plastic pollutionstudies (e.g., Frias et al. 2014; Li et al. 2016). Further-more, the most abundant items of macro-, meso-, andmicroplastics were further identified by spectrophotom-etry. Spectra ranges were set at 4000–400 cm−1, usingthe IRsolution Agent software. The resulting spectrawere directly compared with the reference librarydatabases.

Results

Macroplastics

Based on the NOAA’s classification (Lippiatt et al.2013), a total of 24 categories of macroplastic debriswere recorded in this study. They were bags (mainlyshopping and garbage bags), food wrappers (cookies,powdered juices, etc), beverage bottles (mainly waterand soft drinks), beverage bottle caps (and other productcaps), label bottles, cleaning product containers, person-al care product containers, paint pots, disposable ciga-rette lighters, pens, disposable tableware products, dis-posable hard food containers, disposable foam foodcontainers (cups, etc), straws and stirrers, toys, strappingbands, personal care products (toothbrush and hair-brush, etc), medical products (blister packs, etc), house-hold appliances pieces, plastic cards, rope pieces, fishline, and hose pieces. Subsequently, we summarizedthem into nine wider categories (Table 1).

According to Table 1, food wrappers, bags (plasticfilm), and disposable foam food containers (mainlypackaging for clamshells, trays, and cups) were thedominant macroitems recorded in this study. An averageof 217 macroitems were recorded per transect (i.e., 1.15macroplastics m−2), with 91 of them being food wrap-pers. Beverage bottles were the heaviest group ofmacroplastics, totalizing about 600 g per transect,followed by bags (190 g). An average of 1.23 kg ofplastic was collected from each transect (i.e., 4.9 g m−2).Otherwise, plastic films (bags and food wrappers) cov-ered an average surface of 3.5 m2 per transect. Asexpected, the highest volume was given by bottles(empty bottles), particularly water and soft drinks(Table 1).

Based on the ASTM RIC, Standard Practice forCoding Plastic Manufactured Articles for Resin

Identification (2016) and the FT-IR spectrophotometer,polypropylene (PP) and polystyrene (PS) were the mainresins used in food wrappers. PP was additionally pres-ent in bottle caps and closures. High-density polyethyl-ene (HDPE) and low-density polyethylene (LDPE)were the main plastic resin out of which the bags weremade. Otherwise, HDPE was widely found in otherproducts like personal care products (toothbrushes, hair-brushes, combs, deodorants, and shampoos) andcleaning product containers (floor cleaners; Table 1).

Numerous macroitems made up of expanded poly-styrene (EPS) were recorded, generally fragmented inseveral pieces. Styrofoam food containers were thedominant items composed of this resin, including foambowls, lids, trays, cups, and clamshell boxes. Beveragebottles, cosmetic product containers, hard food con-tainers, and even strapping bands were made up ofpolyethylene terephthalate (PET; Table 1).

Other resins were identified but at relatively lowdensities. The presence of polyvinyl chloride (PVC)was relatively irrelevant in terms of number of itemsand total weight. PVC was found in miscellaneousproducts, from fragments of hoses to blisters. Nylon(generic designation of dry polyamide) was found inlittle pieces of rope and fish lines. Pieces made up ofpolymethylmethacrylate (PMMA; also known as acrylicor acrylic glass) of unknown origin were identified.Finally, several disposable lighters manufactured of sty-rene acrylonitrile (SAN) were registered (Table 1).However, we do not exclude the presence of otherplastic resins occurring at low densities.

Mesoplastics

Foam plastics (EPS) were the dominant mesoplasticcategory (17 items m−2, Table 2), while the heaviestones were hard plastics (1.22 g m−2). The latter exhib-ited several colors, which is a proxy indicator of highvariation in resin composition and origin. Allmesoplastics combined totaled an average of 25 itemsm−2 and 1.9 g m−2, covering a hypothetical area of0.003 m2.

Microplastics

Microfragments of hard plastics and fibers were thedominant items recorded (Table 3). However, foammicroparticles (EPS) represent the largest area

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(6.9 cm2). In total, an average of 704 microplastic frag-ments (m2) was found in shoreline sediments.

Macro-, meso-, and microplastics

Figure 2 shows a large variety of plastic debris solelycollected from transect 1. Note the diversity of manu-facture origins (domestic rather than industrial), usages,consistencies, sizes, colors, shapes, etc.

Table 4 shows that film was clearly the dominantmacroplastic category (in number of pieces), while foamwas for mesoplastics, and hard and fiber were formicroplastics. According to ANOVA results (Table 4),both transects for macroplastic collection were signifi-cantly different between each other, with T1 being thedominant one in number of items. However, samplingstations for mesoplastics located at T1 and T2 were notstatistically different between each other (Table 4). Oth-erwise, significantly higher densities of microplasticswere recorded in sampling stations located at T2.

Figure 3 shows results of the IR spectra of someselected plastic particles. The IR spectrum of HDPE(Fig. 3a) presents the characteristic vibrational bands ofpolyethylene: CH2 stretching (2920 and 2850 cm−1),bending deformation (1473 and 1463 cm−1), CH3 sym-metric deformation (1377 cm−1), weak wagging deforma-tion (1366, 1351, and 1173 cm−1), weak twisting defor-mation (1306 cm−1), and rocking (730 and 720 cm−1).The IR spectrum shown in Fig. 3b is assigned to theLDPE. Even though the IR bands are the same as thoseof HDPE, the intensity of the CH3 symmetric deformationmode at 1377 cm−1 was well defined, indicating a higherconcentration of methyl groups and, therefore, a consid-erable amount of side chains, which is distinctive ofLDPE (Gulmine et al. 2002). The vibrational modesobserved in Fig. 3c match with those of PS. This polymer,which contains aromatic rings, was identified by its groupof bands around (i) 3090 and 2900 cm−1 (aromatic andalkane C–H stretching), (ii) 1600 cm−1 (ring breathingvibration and CH2 deformation), and (iii) 1300 and

Table 1 Summary of the main macroplastic debris and their quantification per transect (transect area = 250 m2) according to number ofitems, weight, area, volume, and length

Type No. of items Weight (g) Area (m2) Volume (L) Length (m) Resin

Bags Film 52.5 190.4 3.49 – – HDPE, LDPE

Food wrappers Film 91 85.3 1.45 – – PP, PS

Hard food container/food service items Hard 12 82.4 – – – PS, PET

Foam food containers Foam 29.5 17.4 – – – EPS

Beverage bottles Hard 9.5 597.1 – 21.88 – PET

Personal care products Hard 2.5 73.7 – 0.33 – HDPE, PET

Cleaning product containers Hard 3.5 68.6 – 2.04 – HDPE, PET

Fish lines Line 0.5 1.7 – – 1.5 Nylon

Others Others 16.5 116.5 – – 1 PMMA, PVC, SAN

Total 217.5 1232.8 4.945 24.24 2.5 10

Resins are sorted by decreasing order of frequency. Dash (−) indicates negligible or absent valuesHDPE: high-density polyethylene; LDPE: low-density polyethylene; PP: polypropylene; PS: polystyrene; PET: polyethylene terephthalate;EPS: expanded polystyrene; Nylon: dry polyamide; PVC: polyvinyl chloride; SAN: styrene acrylonitrile; PMMA: polymethylmethacrylate

Table 2 Mesoplastic average recorded per square meter

No. of items Weight (g) Area (cm2) Volume (mL) Length (cm) Color

Films 1.7 0.0177 5.32 0.001 – TRN, MTRN

Hard plastics 5.7 1.2248 10.3 1.4 – RD, BL, LB, WHI, GRY

Foam plastics 17 0.6913 21.65 5.56 – WHI, YEL

Others 0.7 0.01 – 0.0007 6.5 WHI

Total 25 1.9439 37.26 6.97 6.5 8 colors

TRN: transparent; MTRN: milky transparent; RD: red; BL: blue; LB: light blue; WHI: white; GRY: gray; YEL: yellow

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700 cm−1 (aromatic C–H deformation). The IR spectrumof Fig. 3d is consistent with that of PMMA, characterizedby (i) C–H stretching bands in the region of 3010–2800 cm−1; (ii) CO2 stretching at 2350 cm−1; (iii) n(CO)bands at 2200 and 2120 cm−1; (iv) carbonyl stretchingband at 1750, 1752, 1711, and 1600 cm−1; (v) IR bandsaround 1485 and 1030 cm−1, due to de C–H and CH3

deformation and C–C–O stretching modes; (vi) O–CH3

and CH2 rocking modes between 990 and 800 cm−1; and(vii) C–C stretching bands around 760 and 700 cm−1

(Ennis and Kaiser 2010).

Discussion

Macroplastics

The number of macroplastics significantly differed pertransect (p = 0.023; Table 4). This could be explained byT1’s proximity to a concrete groyne (originating a de-positional area slightly downstream). An average of 217macroplastic items were recorded per transect (i.e., 115items 100 m−2). In comparison, Sciacca and van Arkel(2015) reported an average of 51 macrodebris 100 m−2

Table 3 Microplastic average recorded per square meter

No. of items Weight (g) Area (cm2) Length (cm) Color

Films 36 0 1.69 0 WHI, YEL, OR, TRN

Hard plastics 288 0.073 1.292 0 WHI, GN, LB, OR, TRN, BL, BK, YEL

Foam plastics 116 0.001 6.894 0 WHI

Lines 24 0 0 66 WHI, GN, LB, TRN, BL

Fibers 140 0 0 76.4 WHI, BL

Total 704 0 9.876 142.4 9 colors

TRN: transparent; MTRN: milky transparent; BL: blue; LB: light blue; WHI: white; GRY: gray; YEL: yellow; GN: green; OR: orange; BK:black

Fig. 2 Examples of macro- (a), meso- (b), and microplastics (c–f)recorded in one transect (T1), one quadrat (1 m2), and onemicroquadrat (0.0625 m2), respectively. Microplastic images were

obtained under an optical microscope, where c is a piece of nylon,d piece of PET, e piece of EPS, and f milky transparent piece ofPMMA

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in Bermuda, 33 in Azores, and 26 in Easter Islandbeaches.While these beaches are located on the AtlanticOcean, what should be considered is that the plasticinput is conveyed by rivers and released into oceans,both environments being connected (Morritt et al.2014).

A significant proportion of macroplasticsconsisted of food wrappers, bags, and disposablefoam food containers (Table 1). Polypropylene waswidely recorded in food wrapper/packaging and bot-tle labeling (Table 1). PP is liable to chain degrada-tion from exposure to heat and UV radiation fromsunlight in dry beach sediments, as it has been foundherein. However, PP is extremely resistant to bio-degradation (Nicholson 2006). In addition, the abil-ity of PP to absorb persistent organic pollutants maycause further environmental problems. Little isknown about the effects of PP in freshwater systems.However, Mato et al. (2001) documented 100,000 to1 mi l l i on t imes h ighe r concen t ra t ions ofp o l y c h l o r i n a t e d b i p h e n y l s ( PCB s ) a n ddichlorodiphenyldichloroethylene (DDE) in PPpieces from the sea than in the surrounding water.

Will iams and Simmons (1996) suggestedphotodegradation in river shorelines as the principalcause of sample deterioration for LDPE. These authorsconcluded that the longevity of such plastics is a majorreason for their abundance and widespread distribution

both on river banks and beaches. In line with this, weobserved many LDPE macroitems (mainly grocerybags) between sediments at initial and advanced plasticbreakdown process, and its relevance in number wasevident (Table 1).

According to our results, plastic pollution was moreassociated to domestic solid wastes than to industrialones. This statement is also supported by the fact that nomeso- or microplastic pellets were recorded in this study(pellets are mainly used in plastic production; Kleinet al. 2015). Partial coincident results were found byGasperi et al. (2014), who recorded food wrappers/containers and plastic cutlery as dominant floating de-bris in the Seine River.

Out of all the categories recorded, plastic bags(HDPE and LDPE) outnumbered the other catego-ries in total surface and were the second most abun-dant and heaviest (Table 1). Contrary to this, Morrittet al. (2014) reported a relatively small amount ofplastic bags (< 2%) along the Thames River. It isimportant to say that these authors intercepted sub-merged plastic items using eel fyke nets anchored tothe river bed. To start with, this methodologicaldisparity would be attributed to the design of thisnet which could exclude larger plastic bags (Morrittet al. 2014). Likewise, UK public policies encouragepeople not to use supermarket carrier bags, whichcould also contribute to explain this discrepancy.The monomers making up some plastic bags arethought to be relatively harmless. Yet, these mate-rials can still become toxic by picking up otherpollutants (Rochman et al. 2013).

On the other hand, beverage bottles (PET) werethe heaviest group of macroplastics, totalizing about600 g per transect (Table 1). From a 5-m widetransect at Merthyr Mawr beach, an estuarine beachof South Wales, Williams and Simmons (1996)found 96 plastic bottles per km. In the present study,we have recorded an equivalent to 190 bottles perkm, almost twice that amount. From an ecologicalperspective, bottles could encourage the invasion ofspecies that prefer hard surfaces, and as a result,indigenous species would be displaced (Derraik2002). An example of this is the alien bivalveLimnoperna fortunei. This species attaches stronglyto hard substrate like plastic bottles (Karatayev et al.2010). During our sampling campaign, some aggre-gations of L. fortunei valves were observed attachedto plastic bottles.

Table 4 Average of macro-, meso-, and microplastic items re-corded per square meter

Per m2 Macroitems Mesoitems Microitems

Films 0.574 1.7 36

Hard plastics 0.11 5.7 288

Foam plastics 0.118 17 116

Lines 0.002 0 24

Fibers 0 0 140

Others 0.066 0.7 0

Total 0.87 25.1 704

ANOVA T1 vs. T2 SS1 vs. SS2 SS1 vs. SS2

p 0.023 0.098 0.199

F 5.47 2.96 1.77

Total 1.26 vs. 0.47 46 vs. 4 504 vs. 904

ANOVA comparison between both T1 and T2 transects(macroplastics) and sampling stations for meso- and microplastic.ANOVA data was log(10) transformed

T: transect; SS: sampling station; Total: total number of items pertransect and per sampling station

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Metals are widely used in additive agents duringplastic production, functioning as catalysts, pigments,and plastic stabilizers. For example, lead stearate en-hances smoothness and stability of plastic products madefrom PVC polymer (Minagawa 1996). Nakashima et al.(2012) suggested that PVC products act as a transportingvector of toxic metals to beach environments. Propitious-ly, in this study, PVC (toys and hose pieces; see BOthers^in Table 1) has been detected in low concentrations.

According to Table 1, the prevailing number ofmacroitems was made up of PS, followed by HDPEand EPS. In contrast, a dissimilar composition wasreported by Gasperi et al. (2014) in floatingmacroplastics in the Seine River, where most items werecomposed of PP, PE, and to a lesser extent PET. At leastfrom the beginning, this difference would be attributedto a potential disparity in consumer’s behavior betweenFrance and Argentina.

Mesoplastics

Studies involving micro- and mesoplastic debris haveproliferated in recent years (Collignon et al. 2014; Faureet al. 2015a, b; Young and Elliott 2016). Gündoğdu andÇevik (2017) found a proportion of mesoplastic items of13% with respect to microplastics in pelagic areas ofTurkish coasts. This ratio is similar to that reported byEriksen et al. (2013) and Suaria et al. (2016). However,Jayasiri et al. (2013) reported mesoplastic debris as thedominant fractions by number in recreational beaches ofIndia. In the present study, we found a ratio of 4% ofmesoplastics with respect to microplastics. Establishingthis percentage is important because one fraction couldserve as surrogate of the other one, saving time andresources for future studies.

According to Table 2, 77.7% of the mesoplasticparticles were white/transparent. This finding is in

Fig. 3 Resulting FT-IR spectra for pieces of HDPE (a), LDPE (b), PS (c), and PMMA (d)

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agreement with other studies in beach sediments (Heoet al. 2013; Young and Elliott 2016). This result is ofecological relevance as it is described below. Styrofoam(EPS) was the dominant source of mesoplastic debris(Table 2). Given its low density, it is not surprising thatStyrofoam has been the most common mesoplastic inthe study area. A similar phenomenon was reported byZbyszewski et al. (2014) and Driedger et al. (2015) inthe Great Lakes surface waters and shorelines. Casestudies around the world have reported serious pollutionproblems due to the presence of Styrofoam (Hinojosaand Thiel 2009; Heo et al. 2013; Lee et al. 2013).

Microplastics

Mesh size of sieves and filters used during samplingsurvey and sample processing influences microplasticabundance estimations. However, at present, there is nouniversally adopted methodology or size definition(Hidalgo-Ruz et al. 2012), making direct comparisonsdifficult even when they are unavoidable. Klein et al.(2015) have reported an estimation of 1800–30,000microparticles m−2 in river shore sediments of the Rhineand Main rivers (Germany), which is by far above theaverage reported in the present study (704 particlesm−2). However, it should be noted that these authorsconsidered microplastics down to 63 μm. On the otherhand, Imhof et al. (2013) found an average of 1108microplastic particles m−2 at the north shore of a subal-pine lake (Garda, Italy) and only 108 microplastic par-ticles m−2 at the south shore, considering microplasticsdown to 9 μm. Faure et al. 2015a, b) reported an averageof 1300 microplastics per m2 (> 300 μm) in beachsediments of six Swiss lakes, occurring as follows:2100 in Geneva, 320 in Constance, 700 in Neuchâtel,1100 in Maggiore, 460 in Zurich, and 2500 microparti-cles m−2 in Brienz lakes. The latter methodology andresults are comparable and in accordance with thisstudy, indicating a similar relevance of microplasticcontamination (particularly with the Neuchâtel Lake).

Nevertheless, other studies reported the occurrenceof microplastics in lake sediments but at very low den-sities. Thus, Zbyszewski and Corcoran (2011)accounted for 0–34 microplastic fragments (m2) onshorelines of Huron Lake (Canada). Extending theirshoreline monitoring to the Lakes Erie and St. Clair,Zbyszewski et al. (2014) reported only 0.2–8 items m−2,which are notoriously lower concentrations than in theSetúbal Lake.

In the present study, 72.1% of the microplastics col-lected were white/transparent, a finding in agreementwith other studies (Turner and Holmes 2011; Heo et al.2013; Corcoran et al. 2015; Veerasingam et al. 2016;Young and Elliott 2016). Although filters, scrapers(grazers), and shredders indiscriminately ingestmicroplastics from the water column and sediments,Shaw and Day (1994) noted that some visual predatoryplankt ivorous fish may mistakenly feed onmicroplastics that most closely resemble their zooplank-ton prey. Wright et al. (2013) suggested that prey itemresemblance of microplastics as a result of color maycontribute to the likelihood of ingestion. An examina-tion of stomach contents in mesopelagic marine fishrevealed microplastic color frequencies of 75% white/transparent (Boerger et al. 2010). Greene (1985) sug-gests that microplastic ingestion due to food resem-blance may also apply to pelagic invertebrateplanktivores that are visual raptorial predators.

To date, relatively little is known about microplasticingestion in freshwater environments. However, somestudies have demonstrated that freshwater invertebratesand fish can ingest plastic particles, causing injuries,stress, contaminant bioaccumulation (chemicals inher-ent in plastic), and tumor formation; immune responsedisrupting feeding/swimming; and altering metabolicfunction (Rosenkranz et al. 2009; Imhof et al. 2013;Sanchez et al. 2014; Biginagwa et al. 2016). In thissense, we suggest a potential risk of microplastic inges-tion (mainly white/transparent) by visual predator fish inthe Setúbal Lake, particularly during flooding stageswhen microplastic debris from beaches are availablefor fish by flotation. However, further research is re-quired to fully assess this potential impact.

According to Table 4, macroplastic item surveyswould not serve as surrogates for microplastic items,as proposed by other authors (e.g., Lee et al. 2013). Thiswould be disadvantageous since macroplastic surveysare more easily conducted by researchers (and even byvolunteers; Sheavly 2007).

Finally, the current study demonstrates that plasticdebris is a serious problem in Setúbal Lake and poten-tially in the Paraná system, since both environments aredirectly connected. However, we acknowledge that thepresent data represent a snapshot, and as such, it isdifficult to estimate the extension of the problem in theParaná system.

Results from this study are also important from asocial/educational point of view, since plastic waste is

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often ignored as a pollutant by the society in general(Faure et al. 2015a, b). In the current study, plastic foodwrappers, bottles, and bags were a very visible sign ofpollution, which is more easily understood by the gen-eral population than the Binvisible^ pollutants, likemetals. Solving the visible problems will discouragedisposal of all waste on riverbanks and floodplainsand, hopefully, reduce overall pollution as noted byHeilmann and Whalley (2014).

Conclusions

1. An alarming number of macroplastics were record-ed by comparison with other studies worldwide.Food wrappers (PP), bags (HDPE and LDPE), andbeverage bottles (PET) were the dominantmacroitems. The dominance of household wasteover industrial ones showed the importance ofimplementing consumer awareness-raising strate-gies in the region.

2. Macroplastic surveys would not serve as surrogatesfor meso- or microplastic items, as proposed byother authors. This is disadvantageous sincemacroplastic surveys can be conducted by re-searchers as well as by nonspecialized staff, whohave played crucial roles in debris monitoringprograms.

3. Our results indicated a similar relevance ofmicroplastic contamination regarding other stud-ies, with a predominance of white/transparentmicroparticles. Both facts suggested that visualpredatory planktivorous fish could be underthreat, since they may mistakenly feed onmicroplastics that closely resemble their zoo-plankton prey. Further studies should confirmor reject this suggestion.

4. The large amounts of plastic observed endanger thelake ecosystem and suggest the need to improve theenvironmental policies and educational strategies.

Acknowledgements We thank the reviewers for their thoughtfulreview and Prof. Estela Matthews for substantially improving theEnglish language of the manuscript.

Funding information This study was fully supported by theRufford Foundation, UK (RSG grant; Ref: 21232-1).

References

Biginagwa, F., Mayoma, B., Shashoua, Y., Syberg, K., & Khan, F.(2016). First evidence of microplastics in the African GreatLakes: recovery from Lake Victoria Nile perch and Niletilapia. Journal of Great Lakes Research, 42, 1146–1149.

Boerger, C. M., Lattin, G. L., Moore, S. L., &Moore, C. J. (2010).Plastic ingestion by planktivorous fishes in the North Pacificcentral gyre.Marine Pollution Bulletin, 60(1–2), 2275–2278.

Browne, M. A., Dissanayake, A., Galloway, T. S., Lowe, D. M., &Thompson, R. C. (2008). Ingested microscopic plastic trans-locates to the circulatory system of the mussel, Mytilus edulis(L.) Environmental Science & Technology, 42, 5026–5031.

Castañeda, R., Avlijas, S., & Ricciardi, A. (2014). Microplasticpollution in St. Lawrence River sediments. CanadianJournal of Fisheries and Aquatic Sciences, 71, 1767–1771.

Cheshire, A. C., Adler, E., Barbière, J., Cohen, Y., Evans, S.,Jarayabhand, S., Jeftic, L., Jung, R. T., Kinsey, S., Kusui,E. T., Lavine, I., Manyara, P., Oosterbaan, L., Pereira, M. A.,Sheavly, S., Tkalin, A., Varadarajan, S., Wenneker, B. andWestphalen, G. (2009). UNEP/IOC guidelines on survey andmonitoring of marine litter. UNEP Regional Seas Reportsand Studies No. 186, IOC Technical Series No. 83, 120 p.

Collignon, A., Hecq, J.-H., Galgani, F., Collard, F., & Goffart, A.(2014). Annual variation in neustonic micro- and meso-plastic particles and zooplankton in the Bay of Calvi(Mediterranean–Corsica). Marine Pollution Bulletin., 79,293–298.

Corcoran, P. L., Norris, T., Ceccanese, T., Walzak, M. J., Helm, P.A., &Marvin, C. H. (2015). Hidden plastics of Lake Ontario,Canada and their potential preservation in the sediment re-cord. Environmental Pollution, 204, 17–25.

Derraik, J. G. B. (2002). The pollution of the marine environmentby plastic debris: a review. Marine Pollution Bulletin, 44,842–852.

Driedger, A., Dürr, H., Mitchell, K., & Van Cappellen, P. (2015).Plastic debris in the Laurentian Great Lakes: a review.Journal of Great Lakes Research, 41, 9–19.

Eerkes-Medrano, D., Thompson, R., & Aldridge, D. (2015).Microplastics in freshwater systems: a review of the emerg-ing threats, identification of knowledge gaps andprioritisation of research needs. Water Research, 75, 63–82.

Ennis, C. P., & Kaiser, R. I. (2010). Mechanistical studies on theelectron-induced degradation of polymethylmethacrylate andKapton. Physical Chemistry Chemical Physics, 12, 14902–14915.

Eriksen, M., Mason, S., Wilson, S., Box, C., Zellers, A., Edwards,W., Farley, H., & Amato, S. (2013). Microplastic pollution inthe surface waters of the Laurentian Great Lakes. MarinePollution Bulletin, 77, 177–182.

Faure, F., Demars, C.,Wieser, O., Kunz,M., & deAlencastro, L. F.(2015a). Plastic pollution in Swiss surface waters: nature andconcentrations, interaction with pollutants. EnvironmentalChemistry, 12(5), 582–591.

Faure, F., Saini, C., Potter, G., Galgani, F., de Alencastro, L. F., &Hagmann, P. (2015b). An evaluation of surface micro- andmesoplastic pollution in pelagic ecosystems of the westernMediterranean Sea. Environmental Science and PollutionResearch, 22, 12190–12197.

Environ Monit Assess (2017) 189:581 Page 11 of 13 581

Frias, J. P. G. L., Otero, V., & Sobral, P. (2014). Evidence ofmicroplastics in samples of zooplankton from Portuguesecoastal waters. Marine Environmental Research, 95, 89–95.

Gasperi, J., Dris, R., Bonin, T., Rocher, V., & Tassin, B. (2014).Assessment of floating plastic debris in surface water alongthe Seine River. Environmental Pollution, 195, 163–166.

Greene, C. H. (1985). Planktivore functional groups and patternsof prey selection in pelagic communities. Journal ofPlankton Research, 7(1), 35–40.

Gulmine, J. V., Janissek, P. R., Heise, H. M., & Akcelrud, L.(2002). Polyethylene characterization by FTIR. PolymerTesting, 21, 557–563.

Gündoğdu, S., & Çevik, C. (2017). Micro- and mesoplastics inNortheast Levantine coast of Turkey: the preliminary resultsfrom surface samples. Marine Pollution Bulletin. https://doi.org/10.1016/j.marpolbul.2017.03.002.

Heilmann, D., Whalley, P. (2014). Plastic waste—a very visibleindicator of pollution. GEF/UNDP integrating multiple ben-efits of wetlands and floodplain into improved transboundarymanagement for the Tisza River Basin. http://www.iwlearn.net/experience

Heo, N. W., Hong, S. H., Han, G. M., Hong, S., Lee, J., Song, Y.K., Jang, M., & Shim, W. J. (2013). Distribution of smallplastic debris in cross-section and high strandline onHeungnam Beach, South Korea. Ocean Science Journal,48, 225–233.

Hidalgo-Ruz, V., Gutow, L., Thompson, R. C., & Thiel, M.(2012). Microplastics in the marine environment: a reviewof the methods used for identification and quantification.Environmental Science & Technology, 46, 3060–3075.

Hinojosa, I. A., & Thiel, M. (2009). Foating marine debris infjords, gulfs and channels of southern Chile. MarinePollution Bulletin, 58, 341–350.

Imhof, H. K., Ivleva, N. P., Schmid, J., Niessner, R., & Laforsch,C. (2013). Contamination of beach sediments of a subalpinelake with microplastic particles. Current Biology, 23, 867–868.

Jayasiri, H. B., Purushothaman, C. S., & Vennila, A. (2013).Quantitative analysis of plastic debris on recreational beachesin Mumbai, India. Marine Pollution Bulletin, 77, 107–112.

Karatayev, A. Y., Burlakova, L. E., Karatayev, V. A., &Boltovskoy, D. (2010). Limnoperna fortunei versusDreissena polymorpha: population densities and benthiccommunity impacts of two invasive freshwater bivalves.Journal of Shellfish Research, 29(4), 975–984.

Klein, S.,Worch, E., Knepper, T. P. (2015). Occurrence and spatialdistribution of microplastics in river shore sediments of theRhine-Main area in Germany. https://doi.org/10.1021/acs.est.5b00492.

Latrubesse, E. (2008). Patterns of anabranching channels: theultimate end-member adjustment of mega rivers.Geomorphology, 101, 130–145.

Lechner, A., Keckeis, H., Lumesberger-Loisl, F., Zens, B., Krusch,R., Tritthart, M., Glas, M., & Schludermann, E. (2014). TheDanube so colourful: a potpourri of plastic litter outnumbersfish larvae in Europe’s second largest river. EnvironmentalPollution, 188, 177–181.

Lee, J., Hong, S., Song, Y. K., Hong, S. H., Jang, Y. C., Jang, M.,Heo, N. W., Han, G. M., Lee, M. J., Kang, D., & Shim, W. J.(2013). Relationships among the abundances of plastic debris

in different size classes on beaches in South Korea. MarinePollution Bulletin, 77, 349–354.

Li, J., Qu, X., Su, L., Zhang, W., Yang, D., Kolandhasamy, P., Li,D., & Shi, H. (2016). Microplastics in mussels along thecoastal waters of China. Environmental Pollution, 214,177–184.

Lippiatt, S., Opfer, S., and Arthur, C. (2013). Marine debrismoni to r ing and assessmen t . NOAA Technica lMemorandum NOS-OR&R-46.

Masura, J. Baker, J., Foster, G., Arthur, C. (2015). Laboratorymethods for the analysis of microplastics in the marine envi-ronment: recommendations for quantifying synthetic parti-cles in waters and sediments. NOAA TechnicalMemorandum NOS-OR&R-R-48.

Mato, Y., Isobe, T., Takada, H., Kanehiro, H., Ohtake, C., &Kaminuma, T. (2001). Plastic resin pellets as a transportmedium for toxic chemicals in the marine environment.Environmental Science & Technology, 35, 318–324.

Minagawa, M. (1996). Plastic additives application note. Tokyo:Kogyo Chosakai Publishing Co. Ltd..

Moore, C., Lattin, G., & Zellers, A. (2011). Quantity and type ofplastic debris flowing from two urban rivers to coastal watersand beaches of Southern California. Journal of IntegratedCoastal Zone Management, 11, 65–73.

Morritt, D., Stefanoudis, P. V., Pearce, D., Crimmen, A., & Clark,P. F. (2014). Plastic in the Thames: a river runs through it.Marine Pollution Bulletin, 78, 196–200.

MSFD Technical Subgroup on Marine Litter (2013). Guidance onmonitoring of marine litter in European seas. Joint ResearchCentre Scientific and Policy Reports, European Commission.128 p.

Nakashima, E., Isobe, A., Kako, S., Itai, T., & Takahashi, S.(2012). Quantification of toxic metals derived frommacroplastic litter on Ookushi Beach, Japan. EnvironmentalScience & Technology, 46, 10099–10105.

Nicholson, J. W. (2006). The chemistry of polymers. Cambridge:The Royal Society of Chemistry.

Noik, V. J., & Tuah, P. M. (2015). A first survey on the abundanceof plastics fragments and particles on two sandy beaches inKuching, Sarawak, Malaysia. IOP Conference Series:Materials Science and Engineering, 78, 012035. https://doi.org/10.1088/1757-899X/78/1/012035.

Norén, F. (2007). Small plastic particles in coastal Swedish waters.KIMO report.

Pecorari, S., José de Paggi, S., & Paggi, J. C. (2006). Assessmentof the urbanization effect on a lake by zooplankton. WaterResources, 6(33), 677–685.

RIC, Standard Practice for Coding Plastic Manufactured Articlesfor Resin Identification. (2016). Standard practice for codingplastic manufactured articles for resin identification. ASTMInternational. Retrieved 21 Jan 2016.

Rochman, C. M., Hoh, E., Kurobe, T., & Teh, S. J. (2013).Ingested plastic transfers hazardous chemicals to fish andinduces hepatic stress. Scientific Reports, 3, 3263.

Rosenkranz, P., Chaudhry, Q., Stone, V., & Fernandes, T. F.(2009). A comparison of nanoparticle and fine particle uptakeby Daphnia magna. Environmental Toxicology andChemistry, 28, 2142–2149.

Ryan, P. G., Moore, C. J., van Franeker, J. A., & Moloney, C. L.(2009). Monitoring the abundance of plastic debris in themarine environment. Philosophical Transactions of the

581 Page 12 of 13 Environ Monit Assess (2017) 189:581

Royal Society of London, Series B, Biological Sciences,364(1526), 1999–2012.

Sadri, S. S., & Thompson, R. C. (2014). On the quantity andcomposition of floating plastic debris entering and leavingthe Tamar Estuary, Southwest England. Marine PollutionBulletin, 81, 55–60.

Sanchez, W., Bender, C., & Porcher, J. M. (2014). Wild gudgeons(Gobio gobio) from French rivers are contaminated bymicroplastics: preliminary study and first evidence.Environmental Research, 128, 98–100.

Sciacca, F., van Arkel, K. (2015). Preliminary results from theAzores, Bermuda and Easter Island. Race for water odyssey.http://www.raceforwater.com

Shaw, D. G., & Day, R. H. (1994). Colour- and form-dependentloss of plasticmicro-debris from the North Pacific Ocean.Marine Pollution Bulletin, 28, 39–43.

Sheavly, S. B., (2007). National Marine Debris MonitoringProgram: Final program report, data analysis and summary.Prepared for US Environmental Protection Agency by OceanConservancy, Grant Number X83053401-02. pp. 76.

Song, Y. K., Hong, S. H., Jang, M., Han, G. M., Rani, M., Lee, J.,& Shim, W. J. (2015). A comparison of microscopic andspectroscopic identification methods for analysis ofmicroplastics in environmental samples. Marine PollutionBulletin, 93, 202–209.

Suaria, G., Avio, C. G., Mineo, A., Lattin, G. L., Magaldi, M. G.,Belmonte, G., Moore, C. J., Regoli, F., & Aliani, S. (2016).The Mediterranean plastic soup: synthetic polymers inMediterranean surface waters. Scientific Reports, 6(37551).

Sutherland, W. J., Clout, M., Côté, I. M., Daszak, P., Depledge, M.H., Fellman, L., Fleishman, E., Garthwaite, R., Gibbons, D.W., De Lurio, J., Impey, A. J., Lickorish, F., Lindenmayer,D., Madgwick, J., Margerison, C., Maynard, T., Peck, L. S.,Pretty, J., Prior, S., Redford, K. H., Scharlemann, J. P.,Spalding, M., & Watkinson, A. R. (2010). A horizon scanof global conservation issues for 2010. Trends in Ecology &Evolution, 25, 1–7.

Teuten, E. L., Saquing, J. M., Knappe, D. R., Barlaz, M. A.,Jonsson, S., Björn, A., Rowland, S. J., Thompson, R. C.,Galloway, T. S., Yamashita, R., Ochi, D., Watanuki, Y.,Moore, C., Viet, P. H., Tana, T. S., Prudente, M.,Boonyatumanond, R., Zakaria, M. P., Akkhavong, K.,Ogata, Y., Hirai, H., Iwasa, S., Mizukawa, K., Hagino, Y.,Imamura, A., Saha, M., & Takada, H. (2009). Transport andrelease of chemicals from plastics to the environment and towildlife. Philosophical Transactions of the Royal Society ofLondon. Series B, Biological Sciences, 364, 2027–2045.

Thompson, R. C., Moore, C., vom Saal, F., & Swan, S. (2009).Plastics, the environment and human health: current consen-sus and future trends. Philosophical Transactions of theRoyal Society of London, Series B, Biological Sciences,364, 2153–2166.

Turner, A., & Holmes, L. (2011). Occurrence, distribution andcharacteristics of beached plastic production pellets on theisland of Malta (Central Mediterranean). Marine PollutionBulletin, 62, 377–381.

UNEP (2014). United Nations Environment Programme YearBook 2014: emerging issues in our global environment.ISBN: 978-92-807-3381-5.

Veerasingam, S., Mugilarasan, M., Venkatachalapathy, R., &Vethamony, P. (2016). Influence of 2015 flood on the distri-bution and occurrence of microplastic pellets along theChennai coast, India. Marine Pollution Bulletin, 109, 196–204.

Wagner, M., Scherer, C., Alvarez-Munoz, D., Brennholt, N.,Bourrain, X., Buchinger, S., Fries, E., Grosbois, C.,Klasmeier, J., Marti, T., Rodriguez-Mozaz, S., Urbatzka, R.,Vethaak, A. D., WintherNielson, M., & Reifferscheid, G.(2014). Microplastics in freshwater ecosystems: what weknow and what we need to know. Environmental SciencesEurope, 26, 12.

Williams, A. T., & Simmons, S. L. (1996). The degradation ofplastic litter in rivers: implications for beaches. Journal ofCoastal Conservation, 2, 63–72.

Wong, C. M.,Williams, C. E., Pittock, J., Collier, U., & Schelle, P.(2007). World’s top 10 rivers at risk. Gland: World WildlifeFund.

Wright, S. L., Thompson, R. C., & Galloway, T. S. (2013). Thephysical impacts of microplastics on marine organisms: areview. Environmental Pollution, 178, 483–492.

Yonkos, L. T., Friedel, E. A., Perez-Reyes, A. C., Ghosal, S., &Arthur, C. (2014). Microplastics in four estuarine rivers in theChesapeake Bay, U.S.A. Environmental Science &Technology, 48, 14195–14202.

Young, A. M., & Elliott, J. A. (2016). Characterization ofmicroplastic and mesoplastic debris in sediments fromKamilo Beach and Kahuku Beach, Hawaii. MarinePollution Bulletin, 113, 477–482.

Zalasiewicz, J., Waters, C. N., Ivar do Sul, J., Corcoran, P. L.,Barnosky, A. D., Cearreta, A., Edgeworth, M., Gałuszka, A.,Jeandel, C., Leinfelder, R., McNeill, J. R., Steffen, W.,Summerhayes, C., Wagreich, M., Williams, M., Wolfe, A.P., & Yonan, Y. (2016). The geological cycle of plastics andtheir use as a stratigraphic indicator of the Anthropocene.Anthropocene, 13, 4–17.

Zbyszewski, M., & Corcoran, P. L. (2011). Distribution and deg-radation of fresh water plastic particles along the beaches ofLake Huron, Canada.Water, Air, & Soil Pollution, 220, 365–372.

Zbyszewski, M., Corcoran, P. L., & Hockin, A. (2014).Comparison of the distribution and degradation of plasticdebris along shorelines of the Great Lakes, North America.Journal of Great Lakes Research, 40, 288–299.

Environ Monit Assess (2017) 189:581 Page 13 of 13 581